Aircraft occasionally may have a flight path different than a heading, for example, when landing in a crosswind. Helicopter flying differs from fixed wing aircraft with significantly more vertical and lateral movement and dynamics, including a flight path often quite different than the heading of the helicopter.
When a SVS image is displayed on the Primary Flight Display (PFD) and the SVS view may be centered at an angle other than the heading, the pilot needs to be able to quickly correlate the displayed SVS view to information in the compass. The compass is usually centered at the heading direction so as to correlated and fly according to ATC issued heading instructions. As such, representing the current flight path direction, for example, as a flight path marker, on a typical rotorcraft synthetic vision system (SVS) display typically presents more issues in comparison to the fixed wing aircraft.
One known means involves drawing lines (frustum lines) on the compass from the aircraft symbol, or close to it, toward the edge of the compass's outer ring. This method works well to show the relationship of content inside the compass, especially lateral terrain and the flight plat. However, the frustum lines are less useful if the compass doesn't have a scale associated with it and can impede or conflict with other symbols displayed inside the compass. For example, when the compass area contains lateral deviation symbology for both current and armed navigation (Nav) mode, adding frustum lines can cause difficulties in not only identifying the frustum lines but can interfere with the reading of navigation information. In addition, simple frustum lines do not adequately provide awareness of the large differential between current track and heading conditions.
As a SVS display can be effective with reasonable compressions in order to ensure that the display can be effectively used for precise vertical controls and for scene information and threat displays, methods to effectively display the flight path information relative to the approach target (aim point) is an essential feature for a helicopter SVS primary flight display system.
Accordingly, it is desirable to provide a display system and method allowing the pilot to quickly correlate the content of the SVS display for comparing the view ahead of the aircraft to the aircraft's heading and discern the differences when path and heading are sufficiently different. Furthermore, other desirable features and characteristics of the exemplary embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.